In typical cellular communication networks, a wireless communication device operating in association with the network is required to monitor signaling from the network to be able to detect paging of the wireless communication device by the network. For example, a user equipment (UE) operating in accordance with the specifications for UMTS LTE-A (Third Generation Partnership Project—3GPP—Universal Mobile Telecommunication Standard—Long Term Evolution, Advanced) should receive and attempt to decode the paging channel (PCH) at certain moments in time (e.g. periodically) to monitor whether or not it is paged.
Typically, monitoring of paging should be performed, at least, when the wireless communication device is in idle mode, and in many applications (e.g. for UMTS LTE-A) this protocol may be followed regardless of whether the UE is in idle or connected mode.
Problems related to paging reception may be experienced if one or more neighboring cells use the same carrier frequency as a serving/camped-on cell of a wireless communication device. Then, signals from the one or more neighboring cells act as intra-frequency interference when the paging signal of the serving/camped-on cell is to be received and decoded. This is, of course, particularly problematic if signals of at least one of the one or more neighboring cells, when received at the wireless communication device, are stronger than the signal of the serving/camped-on cell. In this situation, it is not uncommon that the wireless communication device fails to decode the paging signal of the serving/camped-on cell due to the severe intra-frequency interference.
FIG. 1 illustrates an example scenario where a wireless communication device 100 is in coverage of a serving/camped-on cell 121 provided by a network node 120 and of a neighboring cell 111 provided by a network node 110. The wireless communication device 100 is closer to the network node 110 providing the neighboring cell 111 than it is to the network node 120 providing the serving/camped-on cell 121. Hence, an interfering signal 112 from the network node 110 may be stronger than a paging signal 122 from the network node 120 when received at the wireless communication device 100, and the paging in signal 122 may be missed.
Solving this problem by using interference rejection combining (IRC) is typically not possible, at least not if one or more of the intra-frequency neighboring cells are much stronger than the serving/camped-on cell.
The problem may be addressed by using interference cancellation (IC). However, using cell specific reference signal interference cancellation (CRS-IC) may not provide sufficient cancellation since the interference on the paging signals is not only related to the CRS of the neighboring cells, but also to the PDSCH (physical downlink shared channel) of the neighboring cells, and using interference cancellation for paging on PDSCH involves very complex signal generation and reconstruction for the neighboring cells. Typically, the wireless communication device may need to generate symbols of one or more interfering (neighboring) cells, e.g. by channel encoding, scrambling, modulation mapping, layer mapping, precoding and RE (resource element) mapping, which is extremely complex and typically not a practical option.
US 2010/0159929 A1 discloses checking whether a mobile station is experiencing high interference, which may occur when the mobile station fails to decode a paging channel of a serving cell. Upon determining that the mobile station is experiencing high interference, the mobile station selects a set of cells having the same location area identifier as the serving cell from a list of top neighboring cells, selects a cell from the set of cells, and synchronizes with a base station of the selected cell. After synchronizing, the mobile station decodes the paging channel of the selected cell and reads a second page from the paging channel of the selected cell including identical information data as the first page. This approach requires synchronization with the base station of the selected cell and reception of the paging channel of the selected cell, which consumes unnecessary power and introduces considerable delay before the page may be read.
US 2013/0337809 A1 discloses an access terminal dedicating fingers of a rake receiver to listen to paging information transmitted from one or more neighboring cells to avoid missing an incoming page. Such an approach introduces extra complexity and/or unnecessary power consumption, especially if several neighboring cells are to be listened to. Furthermore, fewer rake fingers will be available for the serving cell which may actually compromise paging reception performance in some scenarios.
Therefore, there is a need for alternative methods and devices for paging reception and decoding in intra-frequency interference scenarios.